American Fibertek MRM-1485 - Manual (Page 4)

4
INPUT / OUTPUT CONNECTIONS
The fiber optic connection is made via a ST connector located on the right side of the
unit.
The video output connection is made via a BNC connector on the right side of the unit.
The 75
Ω video output can be looped through typical baseband video inputs of switchers,
recorders and other equipment as required. For proper operation, the output must be
terminated with 75
Ω . For optimum performance the video cables should be the shortest
length of coax practical.
Data input and output connections are made via a terminal block on the right side of the
unit. Follow label on unit for proper orientation of RS485 data input and output. Please
note that two wire applications utilize the four wire data out + and data out - terminals.
DATA CONFIGURATION
The MRM-1485 is shipped from the factory in the RS485 4-wire configuration. In
order to configure the unit for RS485 two wire operation, the unit needs to be
opened up and several switch settings and jumper pins need to be modified using
the internal switch/jumper settings shown on the next page.
The MRM-1485 is shipped from the factory with internal data input and output 120
ohm terminations switched on. In order to remove the internal terminations, the
unit needs to be opened up and several switch settings need to be modified using
the internal switch/jumper settings shown on the next page.
See page 7 for an explanation of termination and offset bias requirements for RS485
data. To open the MRM-1485, remove the screw on the bottom of the module. Also
remove two screws holding the end panel to the chassis on the side with the video and
data connections. Slide PCB assembly out of chassis to access the switch and jumper
locations.